The purpose of this study was to investigate the effects of short-time yoga exercises on physical conditions. The subjects were an experienced male and 15 inexperienced people (10 males and 5 females). They performed each of following three kinds of yoga exercises; 1) uddiyana-bandha (UB), 2) sukhapurvaka-pranayama (SP) and 3) kapalabhati (KB), and a light bicycle exercise (BE) for comparison for ten minutes. Skin electric conductivity (SEC) related to meridian autonomous nervous excitation, heart rate (HR), blood pressure (BP) and oxygen saturation in the arterial blood (SpO_2) were measured. Our findings were as follows: 1. Each of the yoga exercises improved the balance of SEC of the measuring points of hands with SEC of the points of feet. The effect was evident especially in UB. This implies that the excitation level of the sympathetic nerve which controls internal organs was adjusted. The level of SEC was smaller 15 to 30 minutes after the exercises than fefore, which implies that the parasympathetic nervous system was activated. 2. The data on HR and the systolic blood pressure during the performance of the yoga exercises showed that their intensity as a physical exercise was low in comparison with BE. The pulse pressure was smaller, however, 5 to 10 minutes after the exercises than before. This means accentuation of the parasympathetic nervous system. 3. The values of SpO_2 during the performance of SP and KB remained in the normal range. UB caused, however, a gradual decrease of SpO_2, and caused repeatedly a state of transient oxygen-deficiency, which may be interpreted as a much stronger stimulus to respiratory and circulatory systems than ordinary sport exercises. 4. Some of the subjects reported spontaneously that they felt more pleasant and refreshed after the yoga exercises than before. 5. The above findings lead to a conclusion that a short-time performance of the yoga exercises in daily life seems to refresh the human body by activating the autonomous nervous system related to control of respiratory and circulatory systems.